Soybean Cyst Nematode and Soil pH

When discussing Sudden Death Syndrome, or SDS, there are many avenues to navigate.  With soybean varieties broadening their landscape, and varieties becoming more accessible, it leaves growers with many questions.  What can I control, which variety is best for my region, and how do we prevent the spread; just to name a few. 

There are certain aspects of SDS we can control.  The largest being control of Soybean Cyst Nematode (SCN), a vector of SDS.  With any pest, an Integrated Pest Management, or IPM, approach is always the best option for long-term control and suppression.  For SCN many factors come to play when analyzing the spread, growth and reproduction but what can WE control. 

Planting populations, row width, cleaning equipment between fields, seed treatments and variety selection are all great starting points to reducing SCN populations.  For long term control, a study from the University of Wisconsin and Iowa State University sheds light on reducing numbers of SCN through proper fertility management.  This is not only something that growers can control, but a long-term solution. 

This table is copied directly from the article.  It clearly shows, from multi-year data, the reduction of SCN eggs/100 cc of soil as soil pH is reduced.  Some may be wondering, will lowering pH below 6.5 pH limit essential nutrients to the crop?  Yes, it can but everything must be kept within reason.  If SDS is your limiting factor for the highest yield, then it may be the best option to obtain a 6.5 pH rather than a 6.8 for reduced populations.  

The article, by Craig Crau and Nancy Kurtzweil, Department of Plant Pathology, University of Wisconsin, Madison and Gregory L. Tylka, Department of Plant Pathology, Iowa State University, Ames includes many other variables to the equation.  They also show yield differences between SCN-resistant and SCN-susceptible varieties, relationship between soil pH and final population density of SCN at harvest, and the severity of Brown Stem Rot at different pH levels using a selection of soybean varieties.  

For more information on how your soil pH effects Sudden Death Syndrome, Soybean Cyst Nematode and Brown Stem Rot please refer to the attached article.  https://www.mssoy.org/uploads/files/ph-and-scn.pdf